Banca de DEFESA: MARIA EDUARDA BEZERRA LEITE DE QUEIROZ

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MARIA EDUARDA BEZERRA LEITE DE QUEIROZ
DATE: 17/03/2023
TIME: 14:30
LOCAL: Pós-Graduação Engenharia Civil
TITLE:

Autogenous and Drying Shrinkage in High Strength Mortars with Activated Slag and Polypropylene Microfibers

KEY WORDS:

alkali-activated slag mortar; polypropylene fiber; autogenous shrinkage; drying shrinkage.

PAGES: 98
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

Alkali-activated binders have been increasingly studied because they have similar mechanical performance and emit less carbon dioxide compared to Portland cement. However, there are still some barriers to enable the use of activated slag on a large scale, such as its intense shrinkage. In this context, the present work was based on the analysis of the mechanical behavior of slag mortars activated by sodium silicate, using addition of polypropylene fiber (PP). Different contents of polypropylene fiber (0.1%, 0.2% and 0.3%) were tested for each water/binder ratio (0.40, 0.48 and 0.56). The study of drying and autogenous shrinkage for 56 days stands out, the latter with little exploration in the literature. In addition, tensile and compressive strength tests were carried out at 1 day, 3 days, 7 days and 28 days with specimens in submerged cure, and scanning electron microscopy tests on samples tested at 28 days of cure. The results showed that the insertion of polypropylene microfibers caused a decrease in autogenous and drying shrinkage in mortars. Regarding the water/binder ratio, it was also observed that the higher this ratio, the greater the autogenous and drying shrinkage. On the other hand, conflicting results were observed in tensile strength, where the influence of the fibers was not clear. In compressive strength, no improvement was observed as the fiber content increased. Scanning electron microscopy revealed that the fibers ruptured without detaching the alkali-activated matrix and that they may have been slightly degraded by the high alkalinity of the mortar. Finally, it could be concluded that the use of polypropylene microfibers in mortars with activated slag led to a mitigation of autogenous and drying shrinkage for water/binder ratio 0.40 and 0.48, showing low performance for water/binder ratio 0.56.  Even so, the use of microfibers to combat shrinkage proved to be a viable way to make alkali-activated mixtures viable for large-scale applications.

COMMITTEE MEMBERS:
Presidente - 1128124 - ROMILDE ALMEIDA DE OLIVEIRA
Externo à Instituição - ROMILDO MORANT DE HOLANDA - UFRPE
Externa à Instituição - YÊDA VIEIRA PÓVOAS - UPE